Activation of persulfate (PS) and peroxymonosulfate (PMS) and application for the degradation of emerging contaminants

Application of peroxymonosulfate and its activation methods for degradation of environmental organic pollutants: Review

Reports that promote persulfate-based advanced oxidation process (AOP) as a viable alternative to hydrogen peroxide-based processes have been rapidly accumulating in recent water treatment literature. Various strategies to activate peroxide bonds in persulfate precursors have been proposed and the capacity to degrade a wide range of organic pollutants has been demonstrated. Compared to traditional AOPs in which hydroxyl radical serves as the main oxidant, persulfate-based AOPs have been claimed to involve different in situ generated oxidants such as sulfate radical and singlet oxygen as well as nonradical oxidation pathways. However, there exist controversial observations and interpretations around some of these claims, challenging robust scientific progress of this technology toward practical use. This Critical Review comparatively examines the activation mechanisms of peroxymonosulfate and peroxydisulfate and the formation pathways of oxidizing species. Properties of the main oxidizing species are scrutinized and the role of singlet oxygen is debated. In addition, the impacts of water parameters and constituents such as pH, background organic matter, halide, phosphate, and carbonate on persulfate-driven chemistry are discussed. The opportunity for niche applications is also presented, emphasizing the need for parallel efforts to remove currently prevalent knowledge roadblocks.

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Persulfate-Based Advanced Oxidation: Critical Assessment of Opportunities and Roadblocks.

ConspectusCatalytic processes have remarkably boosted the rapid industrializations in chemical production, energy conversion, and environmental remediation. As one of the emerging applications of carbocatalysis, metal-free nanocarbons have demonstrated promise as catalysts for green remediation technologies to overcome the poor stability and undesirable metal leaching in metal-based advanced oxidation processes (AOPs). Since our reports of heterogeneous activation of persulfates with low-dimensional nanocarbons, the novel oxidative system has raised tremendous interest for degradation of organic contaminants in wastewater without secondary contamination. In this Account, we showcase our recent contributions to metal-free catalysis in advanced oxidation, including design of nanocarbon catalysts, exploration of intrinsic active sites, and identification of reactive species and reaction pathways, and we offer perspectives on carbocatalysis for future environmental applications.The journey starts with the dis...

Metal-free carbocatalysis in advanced oxidation reactions

Environmentally friendly and low-cost catalysts are important for the rapid mineralization of organic contaminants in powerful advanced oxidation processes (AOPs). In this study, we reported N-doped graphitic biochars (N-BCs) as low-cost and efficient catalysts for peroxydisulfate (PDS) activation and the degradation of diverse organic pollutants in water treatment, including Orange G, phenol, sulfamethoxazole, and bisphenol A. The biochars at high annealing temperatures (>700 °C) presented highly graphitic nanosheets, large specific surface areas (SSAs), and rich doped nitrogen. In particular, N-BC derived at 900 °C (N-BC900) exhibited the highest degradation rate, which was 39-fold and 6.5-fold of that on N-BC400 and pristine biochar, respectively, and the N-BC900 surpassed most popular metal or nanocarbon catalysts. Different from the radical-based oxidation in N-BC400/PDS via the persistent free radicals (PFRs), singlet oxygen and nonradical pathways (surface-confined activated persulfate–carbon compl...

Catalytic removal of aqueous contaminants on N-doped graphitic biochars: inherent roles of adsorption and nonradical mechanisms.

Non-photochemical production of singlet oxygen via activation of persulfate by carbon nanotubes.

Heterogeneous activation of peroxymonosulfate by sillenite Bi25FeO40: Singlet oxygen generation and degradation for aquatic levofloxacin

Insights into the mechanism of nonradical reactions of persulfate activated by carbon nanotubes: Activation performance and structure-function relationship.

Degradation of 2,4-dichlorophenol by activating persulfate and peroxomonosulfate using micron or nanoscale zero-valent copper

Generation of hydroxyl radicals in the Fenton system (FeII /H2 O2 ) is seriously limited by the sluggish kinetics of FeIII reduction and fast FeIII precipitation Here, boron crystals (C-Boron) remarkably accelerate the FeIII /FeII circulation in Fenton-like systems (C-Boron/FeIII /H2 O2 ) to produce a myriad of hydroxyl radicals with excellent efficiencies in oxidative degradation of various pollutants The surface B-B bonds and interfacial suboxide boron in the surface B12 icosahedra are the active sites to donate electrons to promote fast FeIII reduction to FeII and further enhance hydroxyl radical production via Fenton chemistry The C-Boron/FeIII /H2 O2 system outperforms the benchmark Fenton (FeII /H2 O2 ) and FeIII -based sulfate radical systems The reactivity and stability of crystalline boron is much higher than the popular molecular reducing agents, nanocarbons, and other metal/metal-free nanomaterials

Yongli Zhang

Papers

Non-photochemical production of singlet oxygen via activation of persulfate by carbon nanotubes.

Heterogeneous activation of peroxymonosulfate by sillenite Bi25FeO40: Singlet oxygen generation and degradation for aquatic levofloxacin

Insights into the mechanism of nonradical reactions of persulfate activated by carbon nanotubes: Activation performance and structure-function relationship.

Degradation of 2,4-dichlorophenol by activating persulfate and peroxomonosulfate using micron or nanoscale zero-valent copper

Fast and Long‐Lasting Iron(III) Reduction by Boron Toward Green and Accelerated Fenton Chemistry